Conventionally, self aligning bearings such as spherical roller bearings or spherical Outer Diameter (OD) bearings have been used to correct and/or address angular or radial misalignment between two bearings disposed upon a common shaft or a bearing disposed upon a fixed machine element. Conventionally, a seal is provided about a rotatable shaft such that the bearing can be mounted thereto. More specifically, the Outside Diameter (OD) of the seal is seated into a bearing housing and contacts an outer race of the bearing or housing bore while the seal Inner Diameter (ID) contacts the rotatable shaft or inner race of the bearing. Additionally, a seal may typically be provided on either side of the bearing to both contain lubricating fluid and exclude intrusive contaminates. The bearing is configured to permit slight angular movement (less than 3 degrees).
In known conventional bearings and seal assemblies there are various shortcomings. By way of example, where the seal OD is fixed in a stationary bearing housing or stationary bearing outer race, the seal ID contacts either the bearing inner race or rotatable shaft. As the bearing inner race pivots at the centerline of the bearing an eccentricity and misalignment is created between the seal ID and seal OD. This misalignment reduces the overall life of the bearing and seal assembly.
By way of another example, some known bearing and seal assemblies utilize lip type seals to maintain lubricating fluid within the bearing. Undesirably, if the shaft and seal are not precisely aligned, over contact occurs on one side of the seal and minimal or no contact occurs on the opposite side of the seal. Thus, the integrity of the seal is jeopardized either initially at installation or as a result of excess wear of the seal and shaft.
In still other bearing and seal assembly constructions, where mechanical type seals are utilized, the rotating sealing element is fixed to the rotatable shaft and the stationary sealing element is fixed in a stationary bearing housing. Again, if the seals are not precisely aligned, the seal faces will fail prematurely or will not seal at all. This again reduces the overall life of the bearing and seal assembly.
Currently, the ability of assuring seal integrity of any bearing and seal assembly is dependent upon how well the bearing and seal assemblies are installed and aligned to the rotating shaft. Known art provides various bearing and seal assemblies which permit angular misalignment of the bearing and seal assembly of not more than 3 degrees. However, if the misalignment between the bearing assembly and the rotatable shaft exceeds 3 degrees, such assemblies typically fail prematurely. Accordingly, manufacturers are looking to utilize improved bearing and seal assemblies which obviate the need to precisely align and install the assemblies. In one solution, it would be desirable to produce a self aligning bearing and seal assembly which accommodates angular misalignment greater than 3 degrees and up to 20 degrees. In such a solution, a self aligning bearing and seal assembly would be provided which includes a bearing housing, a bearing unit seated within the bearing housing and a pivot assembly operable for allowing an angular misalignment of a shaft to which the assembly is mounted that is greater than 3 degrees without negatively affecting seal and bearing alignment and integrity.